rtc_event_log2text doesn't currently handle all possible RtcEvent-s.
1. Previous CL - to make sure events are not forgotten in the future, change the succession of if-statements to a switch, so that the compiler would complain if events are ever added, but are not handled here.
2. This CL - add handling of currently-unhandled events.
BUG=webrtc:8111
Change-Id: I5c726c077483b5d85cf8060674c8191a90cb84cc
Reviewed-on: https://webrtc-review.googlesource.com/1244
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Commit-Queue: Elad Alon <eladalon@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#19869}